In general, a DC/DC converter accepts a direct current input at an input voltage level and converts that input into a direct current output at an output voltage level. A typical DC/DC converter includes an oscillator, a transformer, a rectifier and a feedback path. The transformer includes a primary winding which connects to the oscillator, and a secondary winding which connects to the rectifier. The feedback path includes a first portion which connects to the rectifier, and a second portion which connects to the oscillator thus providing a control loop for controlling the oscillator.
During operation, the oscillator receives the direct current input at the input voltage level and converts the input into an alternating current which passes through the primary winding (e.g., “the oscillator chops the input”). Due to magnetic coupling between the primary and secondary windings of the transformer, the alternating current through the primary winding causes a corresponding alternating current to flow through the secondary winding. The rectifier rectifies this corresponding alternating current into the direct current output at the output voltage level. The feedback path provides adjustments back to the oscillator to ensure that the DC/DC converter outputs the proper output voltage level.
There are some situations in which it is desirable for the DC/DC converter to provide electrical isolation between the oscillator and the rectifier. One conventional DC/DC converter with such a feature uses a special transformer called an isolation transformer where the primary winding and the secondary winding are electrically isolated from each other, i.e., the primary winding and the secondary windings do not share a common electrical connection. This DC/DC converter further uses an optocoupler as the feedback path. The optocoupler converts an input electrical signal from the rectifier side of the DC/DC converter to a light signal and then converts the light signal into an electrical output signal on the oscillator side thus maintaining electrical isolation between the oscillator side and rectifier side of the DC/DC converter.